Cataract:

Cataract:

A cataract is a dense, cloudy area that forms in the lens of the eye. A cataract begins when proteins in the eye form clumps that prevent the lens from sending clear images to the retina. The retina works by converting the light that comes through the lens into signals. It sends the signals to the optic nerve, which carries them to the brain.

It develops slowly and eventually interferes with your vision. You might end up with cataracts in both eyes, but they usually don’t form at the same time. Cataracts are common in older people. Over half of people in the United States have cataracts or have undergone cataract surgery by the time they’re 80 years old, according to the National Eye Institute.

Types

There are many types of cataracts:

• Age-related cataracts: The majority of cataracts are related to aging.
• Congenital cataracts: Some babies are born with cataracts. Some children develop them in childhood, often in both eyes. Some congenital cataracts do not affect eyesight, but others do and need to be removed.
• Secondary cataracts: Secondary cataracts usually happen because of another disease in the body (such as diabetes). Secondary cataracts have also been linked to steroid use.
• Traumatic cataracts: An injury to one or both eyes may cause you to develop a traumatic cataract. This can happen either right after the accident or several years later.

Causes

The lens of your eye is mostly water and proteins. As proteins break down over time, they hang around in your eye. These lingering proteins can make your lens cloudy, so it’s hard to see clearly. This is a typical, though unpleasant part of aging.

Some things can speed up the formation of cataracts, such as:

• Diabetes.
• Steroids, common medications to treat conditions like arthritis and lupus.
• Phenothiazine drugs such as chlorpromazine (Thorazine®), used to treat a variety of conditions such as schizophrenia and bipolar disorder.
• Eye surgery or eye injuries.
• Radiation treatment to your upper body.
• Spending a lot of time in the sun without eye protection, like sunglasses.

Symptoms

Signs and symptoms of cataracts include:

• Clouded, blurred or dim vision
• Increasing difficulty with vision at night
• Sensitivity to light and glare
• Need for brighter light for reading and other activities
• Seeing "halos" around lights
• Frequent changes in eyeglass or contact lens prescription
• Fading or yellowing of colors
• Double vision in a single eye

At first, the cloudiness in your vision caused by a cataract may affect only a small part of the eye's lens and you may be unaware of any vision loss. As the cataract grows larger, it clouds more of your lens and distorts the light passing through the lens. This may lead to more-noticeable symptoms.

Diagnosis

To find out if you have cataracts, your doctor will want to know all about your symptoms. They’ll look closely at your eyes and may do some tests including:

Visual acuity test: This is a fancy way of saying "eye chart exam." Your doctor will ask you to read letters from a distance to find out how sharp your vision is. First you'll try it with one eye and then the other. They may also then do a glare test, where they shine a bright light in your eye and then ask you to read the letters.

Slit-lamp exam: This uses a special microscope with a bright light that lets your doctor check different parts of your eye. They'll look at your cornea, the clear outer layer. They'll also examine the iris, the colored part of your eye and the lens that sits behind it. The lens bends light as it enters your eye so you can see things clearly.

Retinal exam: Your doctor puts drops in your eyes to widen your pupils, the dark spots in the middle that control how much light gets in. This lets them get a good look at the retina, the tissue around the back of your eyes, and a better view of the cataract.